pre-intervention quantitative risk factor analysis for ship construction processes

7/25/2019 Pre-Intervention Quantitative Risk Factor Analysis for Ship Construction Processes

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PRELIMINARY SURVEY REPORT:

PRE-INTERVENTION QUANTITATIVE RISK FACTOR ANALYSIS

FOR SHIP CONSTRUCTION PROCESSES

at

JEFFBOAT LLCJeffersonville, Indiana

REPORT WRITTEN BY:Stephen D. Hudock, Ph.D., CSP, NIOSHSteven J. Wurzelbacher, M.S., NIOSH

Ova E. Johnston, NIOSH

REPORT DATE:August 2001

REPORT NO.:EPHB 229-11a

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICESPublic Health Service

Centers for Disease Control and PreventionNational Institute for Occupational Safety and Health

Division of Applied Research and Technology (DART)

Engineering and Physical Hazards Branch (EPHB)4676 Columbia Parkway, Mailstop R-5Cincinnati, Ohio 45226

Approved for public release; distribution is unlimited

Government Purpose Rights


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PLANT SURVEYED: Jeffboat LLC,

A unit of American Commercial Lines Holdings

LLC, 1030 East Market Street

Jeffersonville, Indiana 47130-4330

SIC CODE: 3731

SURVEY DATE: November 9-10, 1999

SURVEY CONDUCTED BY: Stephen D. Hudock, Ph.D., CSPSteven J. Wurzelbacher, Industrial Hygienist

Ova E. Johnston, Engineering Technician

Karl V. Siegfried, MEMIC Safety Services,

Portland, Maine

EMPLOYER REPRESENTATIVES Stephen R. Morris, CSE, CSM, ASP,

CONTACTED: Director of Safety - Shore Facilities

David Temple, NREMTB, Safety Assistant

Gary Neese, Structural Shop Supervisor

EMPLOYEE REPRESENTATIVES Michael Everhart, Chief Union Steward

CONTACTED: Teamsters Local Union 89

MANUSCRIPT EDITED BY: Anne Votaw


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DISCLAIMER

Mention of company names and/or products does not constitute endorsement by the Centers for

Disease Control and Prevention (CDC) or NIOSH.


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ABSTRACT

A pre-intervention quantitative risk factor analysis was performed at various shops and locations

within Jeffboat LLC, a builder of river barges in Indiana, as a method to identify and quantify

risk factors that workers may be exposed to in the course of their normal work duties. This

survey was conducted as part of a larger project, funded through Maritech AdvancedShipbuilding Enterprise and the U.S. Navy, to develop projects to enhance the commercial

viability of domestic shipyards. Four locations were identified: the rake frame subassembly

process, the unloading of angle irons in the steelyard, the honeycomb confined space welding

process for double hull barges, and the shear press operation in the plate shop. The application of

exposure assessment techniques provided a quantitative analysis of the risk factors associated

with the individual tasks. Possible engineering interventions to address these risk factors for

each task are briefly discussed.


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I. INTRODUCTION

IA. BACKGROUND FOR CONTROL TECHNOLOGY STUDIES

The National Institute for Occupational Safety and Health (NIOSH) is the primary Federal

agency in occupational safety and health research. Located in the Department of Health andHuman Services, it was established by the Occupational Safety and Health Act of 1970. This

legislation mandated NIOSH to conduct a number of research and education programs separate

from the standard setting and enforcement functions carried out by the Occupational Safety and

Health Administration (OSHA) in the Department of Labor. An important area of NIOSH

research deals with methods for controlling occupational exposures to potential chemical and

physical hazards. The Engineering and Physical Hazards Branch (EPHB) of the Division of

Applied Research and Technology has been given the lead within NIOSH to study the

engineering aspects of health hazard prevention and control.

Since 1976, EPHB has conducted a number of assessments of health hazard control technology

on the basis of industry, common industrial processes, or specific control techniques. Examplesof the completed studies include the foundry industry; various chemical manufacturing or

processing operations; spray painting; and the recirculation of exhaust air. The objective of each

of these studies has been to document and evaluate effective control techniques for potential

health hazards in the industry or process of interest, and to create a greater general awareness of

the need for or availability of an effective system of hazard control measures.

These studies involve a number of steps or phases. Initially, a series of walk-through surveys is

conducted to select plants or processes with effective and potentially transferable control

concepts or techniques. Next, in-depth surveys are conducted to determine both the control

parameters and the effectiveness of these controls. The reports from these in-depth surveys are

then used as a basis for preparing technical reports and journal articles on effective hazardcontrol measures. Ultimately, the information from these research activities builds the data base

of publicly available information on hazard control techniques for use by health professionals

who are responsible for preventing occupational illness and injury.

IB. BACKGROUND FOR THIS STUDY

The domestic ship building, ship repair, and ship recycling industries have historically had much

higher injury/illness incidence rates than those of general industry, manufacturing, or

construction. For 1998, the latest year available, the Bureau of Labor Statistics reported that

shipbuilding and repair (SIC 3731) had a recordable injury/illness incidence rate of 22.4 per 100

full-time employees (FTE), up from 21.4 in 1997. By contrast, in 1998, the manufacturing sector

reported a rate of 9.7 per 100 FTE, construction reported a rate of 8.8 per 100 FTE, and all

industries reported a rate of 6.7 injuries/illnesses per 100 FTE. When only lost workday cases for

1998 are considered, shipbuilding and repair had an incidence rate of 11.5 per 100 FTE,

compared to manufacturing at 4.7, construction at 4.0, and all industries at 3.1 lost workday


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Injury/Illness Total RecordableIncidence Rate

0

10

20

30

40

50

1990

1991

1992

1993

1994

1995

1996

1997

1998

Year

Cases/100FTE Private industry

Construction

Manufacturing

Boat bldg/rpr

Ship bldg/rpr

Injury/Illness Lost Workday Cases

Incidence Rate

0

5

10

15

20

25

1990

1991

1992

1993

1994

1995

1996

1997

1998

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Cases/100FTE Private industry

Construction

Manufacturing

Boat bldg/rpr

Ship bldg/rpr

injuries/illnesses per 100 FTE. Historical trends for total recordable cases and lost workday

cases have shown downward trends for each of these sectors and industries, as shown in Figures

1 and 2.

Figure 1. Injury/Illness Total Recordable Incidence Rate

Figure 2. Injury/Illness Lost Workday Cases Incidence Rate


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When shipbuilding and repairing are compared to the manufacturing sector for injuries and

illnesses to specific parts of the body that result in days away from work for the year 1997,

shipbuilding is significantly higher in a number of instances. For injuries and illnesses to the

trunk, including the back and shoulder, shipbuilding reported an incidence rate of 207.7 cases per

10,000 FTE, compared to manufacturing at 82.1 cases. For injuries and illnesses solely to the

back, shipbuilding reported 111.1 cases per 10,000 FTE, compared to manufacturings incidencerate of 52.2 cases. For the lower extremity, shipbuilding reported 145.0 cases per 10,000 FTE

compared to manufacturing at 40.8 cases. For upper extremity injuries and illnesses,

shipbuilding reported an incidence rate of 92.2 cases per 10,000 FTE while manufacturing

reported 73.4 cases.

When shipbuilding and repairing are compared to the manufacturing sector, by nature of injury,

for injuries and illnesses resulting in days away from work for the year 1997, shipbuilding is

significantly higher in a number of categories. For sprains and strains, shipbuilding reported an

incidence rate of 237.9 cases per 10,000 FTE, compared to manufacturings incidence rate of

91.0 cases. For fractures, shipbuilding reported 41.7 cases per 10,000 FTE, compared to

manufacturing at 15.8 cases. For bruises, shipbuilding reported 61.3 cases per 10,000 FTE,compared to manufacturing at 21.5 cases. The median number of days away from work for

shipbuilding and repairing is 12 days, compared to manufacturing and private industrys median

of 5 days.

Beginning in 1995 the National Shipbuilding Research Program began funding a project looking

at the implementation of ergonomic interventions at a domestic shipyard as a way to reduce

workers compensation costs and to improve productivity for targeted processes. That project

came to the attention of the Maritime Advisory Committee for Occupational Safety and Health

(MACOSH), a standing advisory committee to OSHA. NIOSH began an internally funded

project in 1997 looking at ergonomic interventions in new ship construction facilities. In 1998,

the U.S. Navy decided to fund a number of research projects looking to improve the commercialviability of domestic shipyards, including projects developing ergonomic interventions for

various shipyard tasks or processes. Project personnel within NIOSH successfully competed in

the project selection process. The Institute currently receives external project funding from the

U.S. Navy through an organization called Maritech Advanced Shipbuilding Enterprise, a

consortium of major domestic shipyards.

Shipyards that participated in the NIOSH project receive an analysis of their injury/illness data,

have at least one ergonomic intervention implemented at their facility, and have access to a web

site documenting ergonomic solutions found throughout the domestic maritime industries. The

implementation of ergonomic interventions in other industries has resulted in decreases in

workers compensation costs and increases in productivity.

Researchers identified seven participating shipyards and analyzed individual shipyard recordable

injury/illness databases by the end of November 1999. Ergonomic interventions will be

implemented in each of the shipyards by the end of December 2000. Intervention follow-up


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analysis will be completed by the end of March 2001. A series of meetings and a workshop to

document the ergonomic intervention program will be held by the end of March 2001.

IC. BACKGROUND FOR THIS SURVEY

Jeffboat LLC was selected for a number of reasons. It was decided that the project should look ata variety of yards based on product, processes, and location. A private shipyard across the Ohio

River from Louisville, Kentucky, Jeffboat LLC performs primarily new vessel construction. This

yard is considered to be a medium- to small-size yard. The primary product of the yard is river

barges of various configurations. Approximately 350 barges are completed each year. Due to

the speed with which vessels are produced (approximately 19 days total), this facility comes

closest to being an assembly line manufacturing facility, somewhat dissimilar to the other

shipyards visited. In addition to the river barges, Jeffboat also produces the occasional towboat

or vessel for the gaming and excursion industries. Jeffboat is a member of the Shipbuilders

Council of America.

Looking at Jeffboat production employees for the period 1995 to 1998, NIOSH researchers founda decline in both the total incidence rate (33% reduction) and the days away from work incident

rate (24% reduction). Among production workers, musculoskeletal disorders represented 27% of

the total cases and 35% of the days away from work cases. Departments within Jeffboat having

the highest rates and numbers of musculoskeletal disorders include the Structural Shop,

Towboats, Hatch Covers, Line 4 Subassembly, Line 1 Hull, Line 1 Sides, Line 4 Hull, and the

Plate Shop. These same departments had the highest rates and number of musculoskeletal

disorders that resulted in days away from work. Occupations having the highest number of

musculoskeletal disorders included welders and shipfitters. Musculoskeletal disorders, including

those resulting in days away from work, most commonly involved the lower back.

There are several caveats that must be considered when analyzing Jeffboat injury data. Forexample, light duty or restricted duty work is not offered to employees who have worked for

fewer than sixty days. Restricted or light duty work is allowed for workers with more than sixty

days, once they have joined the local union (Teamsters). Since there is this disparity between

new hires and full union members, the distribution of Days Away From Work cases may be

inflated by those injuries suffered by the new hires. Also, there may be difficulty in tracking

injury rates for specific workers or crews due to the high turnover rate (approximately 40%).

This may make it difficult to assess intervention effectiveness, especially if crew members

change.


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II. PLANT AND PROCESS DESCRIPTION

IIA. INTRODUCTION

Plant Description: Jeffboat LLC calls itself Americas Largest Inland Shipbuilder. Jeffboat is

located in Jeffersonville, Indiana, across the Ohio river from Louisville, Kentucky. The shipyardhas been in business at its present location since 1939, initially known as the Howard Ship Yards,

then as the Jeffersonville Boat & Machine Company, or Jeffboat, making 123 landing craft, 26

submarine chasers, and hundreds of other vessels for the U.S. Navy during World War II.

Jeffboats primary products now are barges, towboats, and an occasional paddlewheeler. The

shipyard facilities include over a mile of waterfront property, 4 drydocks and approximately 50

acres of property.

Corporate Ties: A unit of American Commercial Lines Holdings LLC

Products: Jeffboat produces approximately 350 barges per year in a variety of configurations

based on client needs, including open hopper barges, double-hull liquid and chemical tankers,covered rake barges, and self-unloading cement barges. Occasionally, towboats and

paddlewheelers for the gaming and excursion industries have been built.

Age of Plant: The site of Jeffboat has been functioning as a shipyard since 1939. Most of the

facility has been updated or rebuilt since that time.

Number of Employees, etc.: At the time of the survey, Jeffboat employed approximately 975

production employees, of which 169 were new hires having less than 90 days experience with the

company. Approximately 45% of the production workers are classified as welders. Annual

turnover has historically been near 40%.

IIB. PROCESS DESCRIPTION

Steelyard Steel plate, beams, and angle iron are delivered to the facility by barge, truck, or train

and is stored at an outside storage yard at the far west end of the property. The steelyard is

serviced by an A-frame crane that retrieves raw material from the yard and positions it for

transfer to the surface preparation area..

Surface Preparation Steel plate and shaped steel are moved from the supply yard by crane into

an automatic surface preparation process. Steel is moved by conveyors through a heating process

to remove any surface moisture, a steel-shot abrasive blasting area to remove any rust or mill

residue, and through a paint priming system that coats the steel with an inorganic zinc coating to

inhibit rusting.

Plate Shop Steel plate is cut to size using numerical control plasma cutting tables. Sections of

plate that need to be shaped are sent through massive rollers to force the steel into the proper


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shape. Smaller shapes are cut with gas burners, cut to size at the shears, or punched at the punch

presses. Sections of steel plate for hull bottoms and sides are welded together at this time.

Subassembly Steel shapes are pieced together and welded to form a variety of subassemblies

for the sides and hulls.

Subassembly Rakes and Sterns Rakes (or the curved bows of the vessels) and sterns are

subassembled nearly to entirety in their own subassembly area

Final Assembly The sides, hulls, rakes, and sterns are pieced together as part of final assembly.

Painting Vessels are painted to customer specifications prior to launch.

IIC. POTENTIAL HAZARDS

Major Hazards: Awkward postures, manual material handling, confined space entry, weldingfumes, ultraviolet radiation from welding, and paint fumes are the major hazards at Jeffboat.

III. METHODOLOGY

A variety of exposure assessment techniques were implemented where deemed appropriate to the

job task being analyzed. The techniques used for analysis include 1) the Rapid Upper Limb

Assessment (RULA); 2) the Strain Index; 3) a University of Michigan Checklist for Upper

Extremity Cumulative Trauma Disorders; 4) the OVAKO Work Analysis System (OWAS); 5) a

Hazard Evaluation Checklist for Lifting, Carrying, Pushing, or Pulling; 6) the NIOSH Lifting

Equation; 7) the University of Michigan 3D Static Strength Prediction Model; and 8) the PLIBELmethod.

The RULA (McAtamney and Corlett, 1993) is a survey method developed to assess the exposure

of workers to risk factors associated with work-related upper limb disorders. On using RULA,

the investigator identifies the posture of the upper and lower arm, neck, trunk, and legs.

Considering muscle use and the force or load involved, the investigator identifies intermediate

scores, which are cross-tabulated to determine the final RULA score. This final score identifies

the level of action recommended to address the job task under consideration.

The Strain Index (Moore and Garg, 1995) provides a semiquantitative job analysis methodology,

that appears to accurately identify jobs associated with distal upper extremity disorders versus

other jobs. The Strain Index is based on ratings of intensity of exertion, duration of exertion,

efforts per minute, hand and wrist posture, speed of work, and duration per day. Each of these

ratings is translated into a multiplier. These multipliers are combined to create a single Strain

Index score.


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The University of Michigan Checklist for Upper Extremity Cumulative Trauma Disorders

(Lifshitz and Armstrong, 1986) allows the investigator to survey a job task with regard to the

physical stress and the forces involved, the upper limb posture, the suitability of the workstation

and tools used, and the repetitiveness of a job task. Negative answers are indicative of conditions

that are associated with the development of cumulative trauma disorders.

The OWAS (Louhevaara and Suurnkki, 1992) was developed to assess the quality of postures

taken in relation to manual materials handling tasks. Workers are observed repeatedly over the

course of the day and postures and forces involved are documented. Work postures and forces

involved are cross-tabulated to determine an action category that recommends if, or when,

corrective measures should be taken.

The NIOSH Hazard Evaluation Checklist for Lifting, Carrying, Pushing, or Pulling (Waters and

Putz-Anderson, 1996) is an example of a simple checklist that can be used as a screening tool to

provide a quick determination as to whether or not a particular job task is comprised of

conditions that place the worker at risk of developing low back pain.

The NIOSH Lifting Equation (Waters et al., 1993) provides an empirical method to compute the

recommended weight limit for manual lifting tasks. The revised equation provides methods for

evaluating asymmetrical lifting tasks and less than optimal hand to object coupling. The

equation allows the evaluation of a greater range of work durations and lifting frequencies. The

equation also accommodates the analysis of multiple lifting tasks. The Lifting Index, the ratio of

load lifted to the recommended weight limit, provides a simple means to compare different

lifting tasks.

The University of Michigan 3D Static Strength Prediction Program is a useful job design and

evaluation tool for the analysis of slow movements used in heavy materials handling tasks. Such

tasks can best be analyzed by describing the activity as a sequence of static postures. Theprogram provides graphical representation of the worker postures and the materials handling

task. Program output includes the estimated compression on the L5/S1 vertebral disc and the

percentage of population capable of the task with respect to limits at the elbow, shoulder, torso,

hip, knee, and ankle.

The PLIBEL method (Kemmlert, 1995) is a checklist method that links questions concerning

awkward work postures, work movements, and design of tools and the workplace to specific

body regions. In addition, any stressful environmental or organizational conditions should be

noted. In general, the PLIBEL method was designed as a standardized and practical assessment

tool for the evaluation of ergonomic conditions in the workplace.

Four specific processes were identified for further analysis. These processes were rake frame

subassemblies within the Structural Shop, angle iron unload within the Steelyard, honeycomb

welding within the Line 4 Hull area, and shear operation within the Plate Shop. Each of these

processes are examined in greater detail below.


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IIIA. RAKE FRAME SUBASSEMBLIES WITHIN STRUCTURAL SHOP

Figure 3. Rake Frame Subassembly Area

IIIA1. Injury Data

The rake frame subassembly area has the highest overall musculoskeletal disorder (MSD)

incidence rate within the shipyard, is second within the shipyard in MSD Days Away From Work

incidence rate at 3.5 cases per 100 FTE, and third within the shipyard in MSD back incidence

rate. Examples of recent injuries include lower back strain when angle iron being lifted slipped,

bursitis in knee aggravated by crawling on stern units, and bilateral wrist tendonitis from

repetitive use of handtools and holding steel in place.

IIIA2. Process

Subassemblies, such as rake frames, or the skeletal framework for the curved bows of tankers,

and chemical and cargo barges, are created in this area. Three stations exist for each type of rake

frame, at approximately 21.5 feet x 36 feet each. Jigs are set-up at ground level and are welded in

place on the steel deck floor. The overall rake frame process is as follows:

1) Delivery of angle irons by overhead crane (ranging in size and shape) to stacks

parallel to the jig set-up.

2) Placement of angle irons manually into the jig, usually done by one worker,

sometimes in tandem lifts. This placement requires workers to bend extremely at

the waist and to lift loads of up to about 125 pounds. Workers who do this job are

very skilled and tend to slide and pivot the larger angle irons into place rather than


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lift the entire load. Smaller irons (ranging in size from 45 to 90 pounds) are still

often lifted entirely by hand.

Figure 4. Worker moving angle iron from stockpile to jig

Figure 5. Worker placing smaller angle iron into jig


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3) Angle irons are adjusted into place by the workers using their hands and gator pry

bar to grip the angle irons. Wedges are then hammered into place to hold the irons

steady in the jig.

4) Horizontal plates at the corners of the rake frame are manually lifted, positioned

on the frame, and held in place by C-clamps, as are the smaller angle irons.

Figure 6. Shipfitter holding angle irons together with C-clamps

5) A team of two welders stick weld the joints of the rake frame that face up. Postures

assumed during welding are typically bent at the waist, kneeling, or sitting on the rake

frame.


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Figure 7. Welding rake frame angle irons while standing

Figure 8. Welding rake frame angle irons while squatting

6) The rake frame subassembly is released by the worker knocking out the wedges

with a hammer. The rake frame subassembly is then picked up, flipped over, and

moved to an area adjacent to the jig by the overhead crane. Frames are stacked in

piles of 6-7 frames.

7) The welders move to the stack of frames and weld the joints that are now facing

up. During this process, the shipfitter and the welders are working at the same


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time so that one frame is being set up as the other is finished welding together.

Approximately 18-21 of these frames are done a day.

The most common trades employed within the Structural Shop are welders and shipfitters.

IIIA3. Ergonomic Risk Factors

During rake frame subassembly, shipfitters undergo awkward postures, including extreme lumbar

flexion and excessive loads to low back. Welders undertake awkward postures, such as extreme

lumbar flexion, shoulder abduction, wrist flexion, both ulnar and radial deviation, and kneeling

on hard surfaces.

IIIA4. Ergonomic Analysis of Shipfitters in Rake Frame Subassembly

Using several of the exposure assessment tools outlined above, an ergonomic analysis was

performed for the shipfitter in the rake frame subassembly task. A RULA analysis was not

deemed appropriate because the primary concern with the shipfitter at this task appeared to bemanual materials handling and poor back posture, and the RULA primarily addresses the upper

limb. An Strain Index analysis was performed (Table 1) and found the following results:

1) TheIntensity of Exertionwas rated as Hard and given a multiplier score of 6, on

a scale of 1 to 13.

2) TheDuration of Exertionof the task was rated as 50% - 79% of the task cycle,

resulting in a multiplier of 2.0, on a scale of 0.5 to 3.0.

3) TheEfforts per Minutewere noted to be between 4 and 8, resulting in a multiplier

of 1.0, on a scale of 0.5 to 3.0.

4) TheHand/Wrist Posturewas rated as Good, resulting in a multiplier of 1.0, on a

scale of 1.0 to 3.0.

5) The Speed of Workwas rated as Normal, resulting in a multiplier of 1.0, on a


6) TheDuration of Task per Daywas rated to be between 2 and 4 hours, resulting in

a multiplier of 0.75, on a scale of 0.25 to 1.50.

The multiplier values for each segment are multiplied together resulting in a final Strain Index

(SI) score. For this task the SI score was 9. An SI score of between 5 and 30 is correlated to an

incidence rate of about 77 distal upper extremity injuries per 100 FTE. Regardless of actual

incidence rate, the SI indicated that this task puts the worker at increased risk of developing a

distal upper extremity injury.


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In applying the University of Michigan Upper Extremity Cumulative Trauma Disorder Checklist

to the rake frame shipfitter task (Table 2), of the 21 possible responses, 8 were negative, 6 were

positive, and 7 were not applicable. Negative responses are indicative of conditions associated

with the risk of developing cumulative trauma disorders.

When the OWAS technique was applied to the rake frame shipfitter task (Table 3), correctivemeasures were suggested for a number of specific subtasks. These subtasks included placing the

angle iron, clamping and unclamping the angle iron, hammering wedges to tighten angle irons in

the jig, de-slagging the welds, and staging the angle irons prior to use.

The NIOSH checklist for manual materials handling consists of 14 items. When applied to the

rake frame shipfitter task (Table 4), 6 responses were positive and 8 negative. In this checklist,

positive responses are indicative of conditions that pose a risk to the worker for developing low

back pain. The higher the percentage of positive responses, the greater the risk of low back pain.

For the rake frame shipfitter task, this percentage was 43%.

The University of Michigan 3D Static Strength Prediction Program was used to analyze eightrake frame shipfitter subtasks (Table 5). Analysis of these subtasks resulted in estimated disc

compression loads, at the L5/S1 disc, to be in excess of the NIOSH Recommended Compression

Limit of 770 pounds for seven of the eight subtasks. The average estimated disc compression

load was 923 pounds. The maximum estimated disc compression load was 1,531 pounds, nearly

twice the recommended limit.

The PLIBEL checklist for the rake frame shipfitter task (Table 6) reported a high percentage (>

70%) of risk factors present for the neck, shoulder, upper back, elbows, forearms, hands, and

lower back. Several environmental and organizational modifying factors were present as well.

IIIA5. Ergonomic Analysis of Welders in Rake Frame Subassembly

A Rapid Upper Limb Assessment was conducted for the rake frame welder tasks (Table 7).

Analyses of four tasks with unique postures and a composite task each resulted in a response to

investigate and change immediately.

An SI analysis was performed for the rake frame welders (Table 8) and resulted in the following:

1) TheIntensity of Exertionwas rated as Somewhat Hard and given a multiplier

score of 3, on a scale of 1 to 13.



3) TheEfforts per Minutewere noted to be nearly continuous at greater than or equal

to 20 per minute, resulting in a multiplier of 3.0, on a scale of 0.5 to 3.0.


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4) TheHand/Wrist Posturewas rated as Fair, resulting in a multiplier of 1.0, on a






The multiplier values for each segment are multiplied together, resulting in a final SI score. For

the rake frame welder tasks the final SI score was 27. An SI score of between 5 and 30 is

correlated to an incidence rate of about 77 distal upper extremity injuries per 100 FTE.

Regardless of actual incidence rate, the SI indicated that this task puts the worker at increased

risk of developing a distal upper extremity injury.


to the rake frame welder task (Table 9), of the 21 items, 10 were negative and 12 were positive (1item answered both positively and negatively). Negative responses are indicative of conditions

associated with the risk of developing cumulative trauma disorders.

When the OWAS technique was applied to the rake frame welder task (Table 10), corrective

measures were suggested for a number of specific subtasks. These subtasks included welding

from inside the rake frame, welding while straddling the rake frame, welding from outside the

rake frame, and de-slagging the welds.

The PLIBEL checklist for the rake frame welder task (Table 11) reported a moderate percentage

(approximately 50%) of risk factors present for the neck, shoulder, upper back, elbows, forearms,

and hands. Several environmental and organizational modifying factors were present as well.


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IIIB. ANGLE IRON UNLOAD IN STEELYARD

Figure 9. Steelyard conveyor system

IIIB1. Injury Data

Injury data specific to workers in the steelyard could not be determined from available

information.

IIIB2. Process

Raw material, primarily steel plate and angle irons, is brought to the shipyard by truck, train, orbarge. Material is placed within the steelyard by the use of an A-frame crane and stored outside

until needed by the various production departments. The task under consideration is the

separation of angle irons from batch loads. The type of angle iron used within the shipyard

varies greatly in size, length, and weight. Common angle irons are 5 inches by 3 inches by 40 feet

in length and 5/16 inch thick. A general description of angle iron separation process follows:

1) A large A-frame crane picks up batch load of angle irons from steelyard and

transports it to an unloading station.

2) After the crane releases the load on a large stand, the steel bands holding the batch

together are cut using a set of shears, and one worker begins separating the load

with a gator bar, which is about 3 feet long, and weighs 12.2 pounds.


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Figure 10. Separating angle irons with gator bar

3) The worker grabs hold of each individual iron with the gator bar and lets it fallonto a sorting table below.

Figure 11. Flipping angle irons onto conveyor with gator bar

4) Two workers, then, pull the angle across the table either by hand or by using large,

long hooks and spread the angle irons across the roller conveyor.


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Figure 12. Workers positioning angle iron on roller conveyor

5) Once the angle irons are placed on the roller conveyor, the angle irons are

transferred to a mobile conveyor section that places the angle irons into the

surfacepreparation process.

IIIB3. Ergonomic Risk Factors

The gator bar worker experiences awkward postures including extreme lumbar flexion and

excessive shoulder loads in separating the angle irons. The unload helpers also experience

awkward postures, including moderate lumbar flexion and moderate shoulder loads in pulling the

angle irons across the roller conveyor.

IIIB4. Ergonomic Analysis of Gator Bar Worker

A Rapid Upper Limb Assessment was conducted for the gator bar worker and the angle iron

separation tasks (Table 12). Analyses of four tasks having unique postures and a composite task

each resulted in a response of 7 on a scale of 1 to 7.

The SI analysis, performed for the gator bar worker separating angle irons (Table 13), obtained

the following results:

1) TheIntensity of Exertionwas rated as Very Hard and given a multiplier score of

9, on a scale of 1 to 13.




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3) TheEfforts per Minutewere recorded to be between 9 and 14 resulting in a

multiplier of 1.5, on a scale of 0.5 to 3.0.

4) TheHand/Wrist Posturewas rated as Bad, resulting in a multiplier of 2.0, on a






The multiplier values for each segment were multiplied together resulting in a final SI score. For

the gator bar worker separating angle iron, the final SI score was 13.5. An SI score of between 5

and 30 is correlated to an incidence rate of about 77 distal upper extremity injuries per 100 FTE.

Regardless of actual incidence rate, the SI indicated that this task put the worker at increased risk

of developing a distal upper extremity injury.


to the gator bar worker separating angle irons (Table 14), of the 21 items, 15 were negative and 6

were positive (1 item answered both positively and negatively, 1 item not answered). Negative

responses are indicative of conditions associated with the risk of developing cumulative trauma

disorders.

When the OWAS technique was applied to the gator bar worker separating angle irons (Table

15), a score of 2 on a 4-point scale was obtained for the subtask of using the jaw end of the gator

bar to flip the angle irons. Analyses of three other subtasks resulted in a score 4 on a 4-point

scale. These subtasks included using the jaw end of the gator bar to separate angle irons, andusing the pry end of the gator bar either to separate the angle irons or to lever the angle irons

over.

The PLIBEL checklist for the gator bar worker separating angle irons (Table 16) reported a high

percentage (approximately 80%) of risk factors present for the elbows, forearms, and hands.

Moderate percentages (approximately 50%) of risk factors were present for the neck, shoulder,

upper back and low back. A high percentage (approximately 80%) of environmental and

organizational modifying factors are present as well.


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IIIB5. Ergonomic Analysis of Steelyard Helper

A Rapid Upper Limb Assessment was conducted for the steelyard helper in the angle iron flip

and layout tasks (Table 17). Analysis of one task resulted in a response of 6 on a 7-point scale.

Analyses of three other tasks with unique postures and a composite task each resulted in a score

of 7, on a scale from 1 to 7.

The SI analysis, performed for the steelyard helper in the angle iron flip and layout tasks (Table

18), provided the following results:





3) TheEfforts per Minutewere recorded to be between 9 and 14 resulting in amultiplier of 1.5, on a scale of 0.5 to 3.0.

4) TheHand/Wrist Posturewas rated a Bad, resulting in a multiplier of 2.0, on a






The multiplier values for each segment are multiplied together resulting in a final SI score. For

the steelyard helper at the angle iron task, the final SI score was 10.1. An SI score of between 5

and 30 is correlated to an incidence rate of about 77 distal upper extremity injuries per 100 FTE.




to the steelyard helper at the angle iron task (Table 19), of the 21 items, 14 were negative and 7

were positive (1 item answered both positively and negatively, 1 item not answered). Negative

responses are indicative of conditions associated with the risk of developing cumulative trauma

disorders.

When the OWAS technique was applied to the steelyard helper at the angle iron task (Table 20),

the subtask of dragging the angle iron along the roller conveyor resulted in a rating of 3, on a


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scale of 1 to 4. Analysis of another subtask, using the jaw end of a gator bar to flip the angle

iron, also resulted in a rating of 3 on a 4-point scale.

The PLIBEL checklist for the steelyard helper at the angle iron task (Table 21) reported a high

percentage (approximately 73%) of risk factors present for the elbows, forearms, and hands. A

moderate percentage (approximately 42%) of risk factors were present for the neck, shoulder, andupper back. A moderate percentage (approximately 60%) of environmental and organizational

modifying factors were present as well.

IIIC. HONEYCOMB WELDING IN LINE 4 HULL AREA

Figure 13. Honeycomb confined space welding at Line 4 Hull area

IIIC1. Injury Data

The honeycomb welding task within the Line 4 Hull area is often the initial job of new hires once

they meet the welding school qualifications. This task also tends to be somewhat difficult. The

worker must enter a 2 foot by 2 foot by 16 foot long section of hull and stitch weld the bottom

steel plate to the vertical supports on both sides for the entire length, using a stick welding

process. The confined space can lead to awkward postures, particularly for larger individuals.

This area of the shipyard is fourth in the overall number of musculoskeletal disorders, fourth in

the number of musculoskeletal disorder Days Away from Work cases, and second in

musculoskeletal disorder actual number of days away from work. All workers in this area are

welders. Recent injuries included four ankle injuries due to slips and trips while moving between

honeycombs; four low back injuries from slips, manual materials lifting, or pulling welding


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leads; three knee injuries from slips and contact stresses; and three arm, wrist, or elbow injuries

from pulling welding leads.

IIIC2. Process

The Line 4 Hull area is responsible for welding the double hulls for chemical and liquid tankers.This involves welding in spaces known as honeycombs, which are 2 feet by 2 feet by 16 feet

long. The bottom plate is welded to the vertical supports on both sides of the honeycomb.

Currently, a stick welding process is used. Typically eight to ten honeycombs can be completed

in a shift by each welder. Ventilation is primarily by blower fan, forcing outside air into the

honeycomb. A detailed report on ventilation interventions for this process can be found

elsewhere.

Figure 14. Constrained posture of confined space honeycomb welder

IIIC3. Ergonomic Risk Factors

The welders must assume constrained postures while crawling to the far end of the honeycomb to

begin welding. This task also includes extreme lumbar flexion in confined spaces, contact stress

on the knees and elbows, pulling and lifting weld leads into and out of the honeycomb,

positioning the blower fan and moving it from one honeycomb to the next, and extreme

environmental temperatures in summer and winter.


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IIIC4. Ergonomic Analysis of Honeycomb Welder in Line 4 Hull Area

A Rapid Upper Limb Assessment was conducted for the honeycomb welder task (Table 22).

Analyses of four tasks with unique postures and a composite task each resulted in a score of 7, on

a scale from 1 to 7.

An SI analysis, performed for the honeycomb welder task (Table 23) obtained the following

results:





3) TheEfforts per Minutewere recorded to be extremely static due to the nature of

the process resulting in a multiplier of 3.0, on a scale of 0.5 to 3.0.

4) TheHand/Wrist Posturewas rated as Fair, resulting in a multiplier of 1.5, on a






The multiplier values for each segment are multiplied together resulting in a final SI score. Forthe honeycomb welder task, the final SI score was 27. An SI score of between 5 and 30 is

correlated to an incidence rate of about 77 distal upper extremity injuries per 100 FTE.




to the honeycomb welder task (Table 24), of the 21 items, 10 were negative and 11 were positive.

Negative responses are indicative of conditions associated with the risk of developing cumulative

trauma disorders.

When the OWAS technique was applied to the honeycomb welder task (Table 25), a score of 2

on a scale from 1 to 4 was obtained, for the subtasks of striking the welding arc and running the

bead, deslagging the weld, and changing out the welding sticks, if the back was not twisted.

Otherwise, if the back was twisted, each of the subtasks resulted in a score of 4 on a scale of 1 to

4.


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The PLIBEL checklist for the honeycomb welder task (Table 26) reported a high percentage

(approximately 80%) of risk factors present for the elbows, forearms, and hands. Moderate

percentages (approximately 50% - 65%) of risk factors were present for the neck, shoulder, upper

back, low back, feet, knees and hips. A high percentage (approximately 80%) of environmental

and organizational modifying factors were present as well.

IIID. SHEAR OPERATION IN THE PLATE SHOP

Figure 15. Shear operation in plate shop

IIID1. Injury Data

The plate shop area of the shipyard included the shear operators. The information for the shear

operators could not be sorted out from the rest of the workers in the plate shop. The plate shop

was first within the shipyard in the actual number of days away from work for musculoskeletal

back injuries. It was also first in the actual number of days away from work for all

musculoskeletal injuries. The plate shop was second within the shipyard in actual number of

restricted or light duty days for musculoskeletal injuries.

IIID2. Process

The primary processes within the plate shop are to cut, size, and shape steel plate required for

hulls and subassemblies using shear machines, automated plasma cutters, and manual cutting

torches. The particular process flow for the shear press is as follows:

1) Raw plates are moved to pallets next to the shear by a jib crane that sits between

stations.

2) Plates are moved manually from pallet to shear.


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3) Cut plates are sorted at the back of the shear at ground level and lifted into carts

Figure 16. Shear operator lifting plate from back of shear

IIID3. Ergonomic Risk Factors

Shear operators often lift awkward loads from the ground-level shear chutes and material supply

pallets. Contact stresses experienced by the shear operator include kneeling on the floor to get

material and contact with the sharp edges of the raw or cut material.

IIID4. Ergonomic Analysis of Shear Operator in Plate Shop


to the shear operator task (Table 27), of the 21 possible responses, 8 were negative, 6 were

positive, and 7 were not applicable. Negative responses are indicative of conditions associatedwith the risk of developing cumulative trauma disorders.

When the OWAS technique was applied to the shear operator task (Table 28), a score of 2, on a

scale from 1 to 4, was obtained for a number of specific subtasks. These subtasks included

positioning the plate at the front of the shear, lifting and moving pieces by crane, and manually

lifting pieces from the back of the shear. If the torso is twisted while lifting, this subtask

response changes to a score of 4, on a 4-point scale.

The NIOSH checklist for manual materials handling consists of 14 items. When applied to the

shear operator task (Table 29), 10 responses were positive and 4 negative. In this checklist,

positive responses are indicative of conditions that pose a risk to the worker of developing low

back pain. The higher the percentage of positive response, the greater the risk of low back pain.

For the shear operator task, this percentage was 71%.


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The NIOSH Lifting Equation was used to analyze the sub-task of manually picking material up

from the back of the shear press. The analysis (Table 30) for this task suggests a recommended

weight limit of 13.7 pounds, given the assumed posture. Given that the typical weight of the

plate is about 20 pounds, it is determined that 95% of the male population and 49% of the female

population can perform this task without an increased risk of low back pain.

The University of Michigan 3D Static Strength Prediction Program was used to analyze two

shear operator subtasks (Table 31). Analysis of these subtasks resulted in estimated disc

compression loads at the L5/S1 disc to be below the NIOSH Recommended Compression Limit

of 770 pounds for both subtasks. The average estimated disc compression load was 591 pounds.

The PLIBEL checklist for the shear operator task (Table 32) reported a moderate percentage

(approximately 50%) of risk factors present for the neck, shoulder, upper back, and lower back.

Several environmental and organizational modifying factors were present as well.

IV. CONTROL TECHNOLOGY

Possible interventions and control technologies are mentioned briefly here. A more detailed

report of possible interventions is in press.

IVA. RAKE FRAME SUBASSEMBLY POSSIBLE INTERVENTIONS

An adjustable jig (a jig top placed on a lift table) may offer a solution, and it may be that one jig

can be made to fit all three rake frames. This would open more floor space and eliminate the

need for the welders and shipfitter to bend. Possible problems with this approach are that some

of the workers prefer the low height of the jig because the angles can be pivoted and maneuvered

into place easily. Another concern is that the jig would be too high for the crane to offload, butthis would not be a problem if the jig could be again lowered when unloaded. Also, there are

concerns that the welders would trip over the raised rake frame, although no welds actually

require the welder to be inside of the frame while welding. The only reason that they currently

stand inside of the frame while welding is because the angle irons are stacked up parallel to the

jig approximately 1 foot away and impede getting around the outside of the frame. This means

that the stacking of the material would have to be changed too if the jig was raised, unless the

frame could be rotated as it was raised, which might be possible if engine stand type lifts were

used. A rotatable jig would also eliminate the need for the crane to flip the frame and also

eliminate the problem of welding the frames that are stacked on the ground first. Two years ago,

a number of similar changes were made in other areas of the structural shop. Coincidentally or

not, the MSD incidence rate dropped dramatically from 16 in 1997 to 5 in 1998.


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IVB. ANGLE IRON UNLOAD IN STEELYARD POSSIBLE INTERVENTIONS

An uneven and tilted surface on the stand may help to break the load up as it is released from the

crane. Changes in how the load is slung and/or handled by the crane may also help. A simple

push mechanism on the unloading table would eliminate the need for the two workers who hook

and pull each angle across the table.

IVC. CONFINED SPACE WELDING ON LINE 4 HULL POSSIBLE INTERVENTIONS

Possible interventions include changing the weld process from stick to wire welding, using

creeper carts that would allow the worker to roll to the back of the honeycomb section, installing

automatic welding systems, and improving ventilation systems.

IVD. SHEAR OPERATION IN PLATE SHOP POSSIBLE INTERVENTIONS

The primary intervention for the plate shop shear operator is to provide adjustable lift tables for

raw plates at the front of the shear and also for the shear chute at the back of the machine.

V. CONCLUSIONS AND RECOMMENDATIONS

Four work processes within a barge building operation were surveyed to determine the presence

of risk factors associated with musculoskeletal disorders. The rake frame subassembly task

requires workers in the shipfitter trade to maneuver long steel angle irons into position in a

pattern laid out on the shops steel floor. These long angle irons can weigh approximately 240

pounds and are slid or bounced into position between jigs welded onto the floor. Smaller angle

irons and steel plates are manually placed to form cross members or corner supports. The

combination of manual materials handling and awkward posture of bending the torso to place thematerial near floor level results in a job the can be considered high in musculoskeletal disorder

risk factors. Six separate exposure assessment techniques were used to quantify the risk factors

associated with this shipfitter job. A possible intervention is raising the work surface by

installing a lift table to hold the jig pattern for the rake frame, thereby eliminating the bent torso

for much of the task. Welders who join the individual pieces of steel also exhibit awkward

postures while working near floor level. By raising the work surface, these awkward postures are

minimized.

The unloading of angle iron in the steelyard was also analyzed using a number of exposure

assessment techniques. The high amount of effort required to separate and flip individual pieces

of long angle iron are some of the risk factors associated with this process. Possible

interventions include angling the surface of the stock table to encourage the stack of angle irons

to loosen when dropped by the yard crane, and automating some of the processes to eliminate the

pulling of angle irons into position across the roller conveyor.

The honeycomb welder task in the manufacture of double hull sections requires the worker to

enter a confined space and weld two seams between vertical supports and the bottom steel plate.

This process can be improved from current conditions by changing ventilation set-ups, changing


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from stick to wire welding, or by automating the welding process. This last option may be the

most desirable because it removes the worker from exposure to risk factors. Otherwise, the

constrained postures, exposure to contact stresses in the knees and elbows, and exposure to some

welding fumes would still be present.

The shear operator in the plate shop often bends at the waist to pick up pieces of steel, eitherfrom a supply bin or from the tray at the back of the shear machine. Manually lifting the pieces

of steel from near floor level results in undue stress on the back of the workers. By incorporating

lift tables or tilting pallet jacks into areas both in front and behind the shear machine, one can

minimize the stress on the workers backs. Each of the interventions highlighted here for each of

the four processes will be discussed in much greater detail in a forthcoming report.

It is recommended that further action be taken to mitigate the exposure to musculoskeletal risk

factors within each of the identified tasks. The implementation of ergonomic interventions has

been found to reduce the amount and severity of musculoskeletal disorders within the working

population in various industries. It is suggested that ergonomic interventions may be considered

for implementation at Jeffboat to minimize hazards in the identified job tasks.

VI. REFERENCES

Kemmlert, K. A Method Assigned for the Identification of Ergonomic Hazards PLIBEL.

Applied Ergonomics, 1995, 26(3):199-211.

Lifshitz, Y. and T. Armstrong. A Design Checklist for Control and Prediction of Cumulative

Trauma Disorders in Hand Intensive Manual Jobs. Proceedings of the 30 thAnnual

Meeting of Human Factors Society, 1986, 837-841.

Louhevaara, V. and T. Suurnkki. OWAS: A Method for the Evaluation of Postural Load during

Work. Training Publication No. 11, Institute of Occupational Health, Helsinki, Finland,

1992.

McAtamney, L. and E. N. Corlett. RULA: A Survey Method for the Investigation of Work-

Related Upper Limb Disorders, Applied Ergonomics, 1993, 24(2):91-99.

Moore, J. S. and A. Garg. The Strain Index: A Proposed Method to Analyze Jobs for Risk of

Distal Upper Extremity Disorders, American Industrial Hygiene Association Journal,

1995, 56:443-458.

University of Michigan Software, 3D Static Strength Prediction Program Version 4.0, 3003

State St., #2071, Ann Arbor, MI 48109-1280, Copyright 1997 The Regents of The

University of Michigan.

Waters, T. R., V. Putz-Anderson, A. Garg, and L. J. Fine. Revised NIOSH Equation for the

Design and Evaluation of Manual Lifting Tasks, Ergonomics, 1993, 36(7):749-776.


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Waters, T. R. and V. Putz-Anderson. Manual Materials Handling, Ch. in Occupational

Ergonomics: Theory and Applications, ed. by A. Bhattacharya and J. D. McGlothlin,

Marcel Dekker, Inc., New York, 1996, pp. 329-349.


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APPENDIX

ERGONOMIC ANALYSIS TABLES


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A1. RAKE FRAME SHIPFITTERS

Table 1. Rake Frame Shipfitter Strain Index

Strain Index: Distal Upper Extremity Disorders Risk Assessment

(Moore and Garg, 1995)Date Facility Area/Shop Task

11/9/99 Jeffboat Structural Shop Rake Frame Shipfitting

1. Intensity of Exertion: An estimate of the strength required to perform the task one time. Circle the

rating after using the guidelines below; then fill in the corresponding multiplier in the bottom far right

box.

Rating

Criterion

% MS(percentage of

maximal

strength)

Borg Scale(Compare to

Borg Cr-10

Scale)

Perceived Effort Rating Multiplier

Light < 10% < or = 2 barely noticeable or relaxedeffort

1 1

Somewhat

Hard

10% - 29% 3 noticeable or definite effort 2 3

Hard 30% - 49% 4 - 5 obvious effort; unchanged

facial expression (*28% -

38% of observed time > =

Hard)

3 6

Very Hard 50% - 79% 6 - 7 substantial effort; changes to

facial expression

4 9

Near

Maximal

> or = 80% > 7 uses shoulder or trunk to

generate force

5 13

Intensity of Exertion Multiplier 6


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Table 1. Rake Frame Shipfitter Strain Index (continued)

2. Duration of Exertion (% of cycle): Calculated by measuring the duration of all exertions during an

observation period, then dividing the measured duration of exertion by the total observation time and multiplying

by 100. Use the worksheet below and circle the appropriate rating according to the rating criterion; then fill in the

corresponding multiplier in the bottom far right box.*NOTE: If duration of exertion is 100% (as with some static

tasks), then efforts/ minute multiplier should be set to 3.0

Worksheet:

% Duration of Exertion

= 100 x duration of all exertions (sec)

Total observation time (sec)

= 100 x 546 (sec)/ 984 (sec)

= 55%

*for cycle 2 ndkeel frame

Rating Criterion Rating Multiplier

< 10% 1 0.5

10% - 29% 2 1.0

30% - 49% 3 1.5

50% -79% 4 2.0

> or = 80% 5 3.0

Duration of Exertion Multiplier 2.0

3. Efforts per Minute: Measured by counting the number of exertions that occur during an

observation period; then dividing the number of exertions by the duration of the observation period,

measured in minutes. Use the worksheet below and circle the appropriate rating according to the rating

criterion; then fill in the corresponding multiplier in the bottom far right box. *NOTE: If duration of

exertion is 100% (as with some static tasks), then efforts/ minute multiplier should be set to 3.0

Worksheet:

Efforts per Minute

= number of exertions

Total observation time (min)

= [total # of efforts for observed period,

67/ Total observed time (min)

16.39]

= 4.1


< 4 1 0.5

4 - 8 2 1.0

9 -14 3 1.5

15 -19 4 2.0

> or = 20 5 3.0

Efforts per MinuteMultiplier 1.0


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4. Hand/ Wrist Posture: An estimate of the position of the hand or wrist relative to neutral position.

Circle the rating after using the guidelines below; then fill in the corresponding multiplier in the

bottom far right box.

Rating

Criterion

Wrist

Extension

Wrist

Flexion

Ulnar

Deviation

Perceived

Posture

Rating Multiplier

Very Good 0 -10

degrees

0 - 5

degrees

0 - 10

degrees

perfectly neutral 1 1.0

Good 11 - 25

degrees

6 - 15

degrees

11 -15

degrees

near neutral

(*estimated, no

RULA done)

2 1.0

Fair 26 -40

degrees

16 - 30

degrees

16 - 20

degrees

non-neutral 3 1.5

Bad 41 - 55

degrees

31 - 50

degrees

21 -25

degrees

marked deviation 4 2.0

Very Bad > 60

degrees

> 50

degrees

> 25 degrees near extreme 5 3.0

Hand/ Wrist PostureMultiplier 1.0

5. Speed of Work: An estimate of how fast the worker is working. Circle the rating on the far right

after using the guidelines below; then fill in the corresponding multiplier in the bottom far right box.

Rating

Criterion

Compared to MTM Perceived Speed Rating Multiplier

Very

Slow

< or = 80% extremely relaxed pace 1 1.0

Slow 81% - 90% taking ones own time 2 1.0

Fair 91% - 100% normal speed of motion 3 1.0

Fast 101% - 115% rushed, but able to keep up 4 1.5

Very Fast > 115% rushed and barely or unable tokeep up

5 2.0

Speed of Work Multiplier 1.0


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6. Duration of Task per Day: Either measured or obtained from plant personnel. Circle the rating on

the right after using the guidelines below; then fill in the corresponding multiplier in the bottom far

right box.

Worksheet:

Duration of Task per Day (hrs)

= duration of task (hrs) +

duration of task (hrs) + ....

= (22 frames per day @ 20 minutes per

frame-- from mgmt-- 7.3 hrs of frame

cycle time @ .55 duration of exertion

(See #2) = 4 hrs per day)


< or = 1 hrs 1 0.25

1 - 2 hrs 2 0.50

2 - 4 hrs 3 0.75

4 - 8 hrs 4 1.00

> or = 8 hrs 5 1.50

Duration of Task per Day Multiplier 0.75

Calculate the Strain Index (SI) Score: Insert the multiplier values for each of the six task variables into

the spaces below; then multiply them all together.

Intensity

of

Exertion

6.0 X

Duration

of

Exertion

2.0 X

Efforts

per

Minute

1.0 X

Hand/

Wrist

Posture

1.0 X

Speed of

Work

1.0 X

Duration

of Task

0.75

=

SI SCORE

9.0

SI Scores are used to predict Incidence Rates of Distal Upper Extremity (DUE) injuries per 100 FTE:

- SI Score < 5 is correlated to an Incidence Rate of about 2 DUE injuries per 100 FTE;

- SI Score of between 5-30 is correlated to an Incidence Rate of about 77 DUE injuries per

100 FTE;

- SI Score of between 31-60 is correlated to an Incidence Rate of about 106 DUE injuries per

100 FTE;

- SI Score > 60 is correlated to an Incidence Rate of about 130 DUE injuries per 100 FTE.


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Table 2. Rake Frame Shipfitter UE CTD Checklist

Michigan Checklist for Upper Extremity (UE) Cumulative Trauma Disorders (CTD)

(Lifshitz and Armstrong, 1986)

Date Facility Area/Shop Task


Risk Factors No* Yes

1. Physical Stress

1.1 Can the job be done without hand/ wrist contact with sharp edges N

1.2 Is the tool operating without vibration? Y

1.3 Are the workers hands exposed to temperature >21degrees C (70 degrees F)? N Y

1.4 Can the job be done without using gloves? N

2. Force

2.1 Does the job require exerting less than 4.5 kg (10 lbs.) of force? N

2.2 Can the job be done without using finger pinch grip? Y

3. Posture

3.1 Can the job be done without flexion or extension of the wrist? N

3.2 Can the tool be used without flexion or extension of the wrist? n/a n/a

3.3 Can the job be done without deviating the wrist from side to side? Y

3.4 Can the tool be used without deviating the wrist from side to side? Y

3.5 Can the worker be seated while performing the job? N

3.6 Can the job be done without clothes wringing motion? Y

4. Workstation Hardware

4.1 Can the orientation of the work surface be adjusted? N

4.2 Can the height of the work surface be adjusted? N

4.3 Can the location of the tool be adjusted? n/a n/a

5. Repetitiveness

5.1 Is the cycle time longer than 30 seconds? Y

6. Tool Design

6.1 Are the thumb and finger slightly overlapped in a closed grip? n/a n/a

6.2 Is the span of the tools handle between 5 and 7 cm (2-2 3/4 inches)? n/a n/a

6.3 Is the handle of the tool made from material other than metal? n/a n/a

6.4 Is the weight of the tool below 4 kg (9 lbs.)? n/a n/a

6.5 Is the tool suspended? n/a n/a

TOTAL 8 7

* No responses are indicative of conditions associated with the risk of CTDs


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Table 3. Rake Frame Shipfitter OWAS

OWAS: OVAKO Work Analysis System

(Louhevaara and Suurnkki, 1992)



Risk Factor WorkPhase 1

Place

Angle

Irons

Work

Phase

2

Clamp

/ Un-

clamp

Work

Phase 3

Hammer

Wedges

Work

Phase

4

Deslag

Work

Phase 5

Stage

Angles

Work

Phase 6

Rest

Work

Phase 7

Un-

defined

Work

Phase 8

Torch

Cut

Work

Phase 9

Place

Angle

Pieces

TOTAL Combination

Posture Score

3, 4 2, 4 2, 4 2, 4 3, 4 1 1 2 2, 3, 4

Common Posture Combinations (collapsed across work phases)

Back 4 1 2 4 2 2 1

Arms 1 1 1 1 1 1 1

Legs 7 1 4 4 7 4 2

Posture Repetition (%

of working time)

51 45 4 51* 51* 55* 4*

Back % of Working

Time Score

3 1 1 3 2 2 1

Arms % of Working

Time Score

1 1 1 1 1 1 1

Legs % of Working

Time Score

1 1 1 3 1 3 1

ACTION CATEGORIES:

1 = No corrective measures

2 = Corrective measures in near future

3 = Corrective measures as soon as possible

4 = Corrective measures immediately


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Table 3. Rake Frame Shipfitter OWAS (continued)

Risk Factor WorkPhase 1

Place

Angle

Irons

Work

Phase 2

Clamp/

un-

clamp

Work

Phase 3

Hammer

Wedges

Work

Phase

4

Deslag

Work

Phase 5

Stage

Angles

Work

Phase

6

Rest

Work

Phase 7

Un-

defined

Work

Phase

8

Torch

Cut

Work

Phase 9

Place

Angle

Pieces

Posture

Back1 = straight

2 = bent forward, backward

3 = twisted or bent sideways

4 = bent and twisted or bent

forward and sideways

2,4 2,4 2,4 2,4 2,4 1 1 2 2,4

Arms1 = both arms are below

shoulder level

2 = one arm is at or above

shoulder level

3 = both arms are at orabove shoulder level

1 1 1 1 1 1 1 1 1

Legs1 = sitting

2 = standing with both legs

straight

3 = standing with the weight

on one straight leg

4 = standing or squatting

with both knees bent

5 = standing or squatting

with one knee bent

6 = kneeling on one or both

knees

7 = walking or moving

7 4, 7 4,7 4,7 4,7 1,2 1,2 4 4,7

Load/ Use of Force

1 = weight or force needed

is = or 22lb < 44 lb)

3 = weight or force > 20 kg

(>44 lb)

Phase Repetition

% of working time:

(0,10,20,30,40,50,60,70,80,90,100)

10 18 7 13 1 5 40 4 2


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Table 4. Rake Frame Shipfitter NIOSH Manual Materials Handling Checklist

NIOSH Hazard Evaluation Checklist for Lifting, Carrying, Pushing, or Pulling

(Waters and Putz-Anderson, 1996)



RISK FACTORS YES NO

General

1.1 Does the load handled exceed 50 lb? Y (usually)

1.2 Is the object difficult to bring close to the body because of its size, bulk, or shape? Y

1.3 Is the load hard to handle because it lacks handles or cutouts for handles, or does it have

slippery surfaces or sharp edges?

Y

1.4 Is the footing unsafe? For example, are the floors slippery, inclined, or uneven? Y (fixtures in way)

1.5 Does the task require fast movement, such as throwing, swinging, or rapid walking? N

1.6 Does the task require stressful body postures such as stooping to the floor, twisting,

reaching overhead, or excessive lateral bending?

Y (extreme lumbar

flexion)

1.7 Is most of the load handled by only one hand, arm, or shoulder? N

1.8 Does the task require working in environmental hazards, such as extreme temperatures,

noise, vibration, lighting, or airborne contamination?

Y (welding,

machinery in

proximity, )

1.9 Does the task require working in a confined area? N

Specific

2.1 Does the lifting frequency exceed 5 lifts per minute (LPM)? N (LPM = 0.67

over total cycle

time, but lifts areperformed in rapid

succession at a

frequency of 2

LPM)

2.2 Does the vertical lifting distance exceed 3 feet? N (seldom)

2.3 Do carries last longer than 1 minute? N

2.4 Do tasks which require large sustained pushing or pulling forces exceed 30 seconds

duration?

N (usually < = 10)

2.5 Do extended reach static holding tasks exceed 1 minute? N

TOTAL 6 (43%) 8 (57%)* YES responses are indicative of conditions that pose a risk of developing low back pain; the larger the percentage ofYES responses, the

greater the risk.


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38

Table 5. Rake Frame Shipfitter 3D Static Strength Prediction Program

3D Static Strength Prediction Program

(University of Michigan, 1997)



Work Elements:

Manual Placement of Angle Iron Rake Frame

Components

Disc Compression (lb) @ L5/S1

(Note: NIOSH Recommended Compression Limit (RCL) is 770

lb)

Angle RF2weighs 133 lb; lifts one end off

stack pivots angle, then drops into place;

33.25 lb per arm (frame #3960)

1389(middle of lift)

Curved angle RF1weighs 246 lb; lifts one

end, pivots into place, lowers load with

control; 123 lb lifted, 61.5 lb per arm (frames

#4320, #4350)

857(middle of lift)

1531 (end of lift)

Angle RF3weighs 125 lb; lifts one end off

stack, and pivots into place, lowers load, then

drops into place; lifts @ 62.5 lb or 31.25 lb

per arm (frames #6030, #6060, #6119)

926(beginning of lift)

597 (middle of lift)

1021(end of lift)

Angle RF4weighs 47 lbs; shipfitter lifts one

end with one hand; lifts 23.50 lb by right arm

(frame #7920), then lowers entire angle; lifts

23.50 lb per arm (frame #7980)



Angle RT-3 weighs 65 lb; lifts one end with

one hand off stack; 32.50 lb by right arm(frame #8550). Then, uses two arms to carry

angle into place; 32.50 lb per arm (frame

#8700)



Angle RT-1 weighs 95 lb; lifts one end with

one hand off stack before using two to drag it

into place; 47.50 lb by right arm for initial lift

(frame #9810)


Angle RT-2weighs 70 lb; lifts one end with

one hand off stack before using two hands to

drag it into place; 35 lb by right arm (frame

#10980)

709 (beginning of lift)

Angle RF-5 weighs 52 lb; lifts one end with

both hands off stack before using two to lift it

into place; 26 lb lifted per arm (frame #11150,

11700)




43/102

39

Table 6. Rake Frame Shipfitter PLIBEL

PLIBEL Checklist

(Kemmlert, 1995)



Section I: Musculoskeletal Risk Factors

Methods of Application:

1) Find the injured body region, answer yes or no to corresponding questions, or

2) Answer questions, score potential body regions for injury risk.

Musculoskeletal Risk Factor Questions Body Regions

Neck, Shoulder,

and Upper Back

Elbows,

Forearms,

Hands

Feet Knees

and

Hips

Low

Back

1: Is the walking surface uneven, sloping, slippery or

nonresilient?

Y Y Y

2: Is the space too limited for work movements or work

materials?

Y Y Y Y Y

3: Are tools and equipment unsuitably designed for the

worker or the task?

Y Y Y Y Y

4: Is the working height incorrectly adjusted? Y Y

5: Is the working chair poorly designed or incorrectly

adjusted?

N N

6: If work performed standing, is there no possibility to sit

and rest?

N N N

7: Is fatiguing foot pedal work performed? N N

8: Is fatiguing leg work performed? For example, ...

a) repeated stepping up on stool, step etc.. N N N

b) repeated jumps, prolonged squatting or kneeling? N N N

c) one leg being used more often in supporting the body? N N N

9: Is repeated or sustained work performed when the back

is:

a) mildly flexed forward? Y Y

b) severely flexed forward? Y Y

c) bent sideways or mildly twisted? Y Y

d) severely twisted? Y Y


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40

Table 6. Rake Frame Shipfitter PLIBEL (continued)

10: Is repeated or sustained work performed when the neck

is:

a) flexed forward? Y

b) bent sideways or mildly twisted? Y

c) severely twisted? N

d) extended backwards? N

11: Are loads lifted manually? Notice factors of importance

as:

a) periods of repetitive lifting Y Y

b) weight of load Y Y

c) awkward grasping of load Y Y

d) awkward location of load at onset or end of lifting Y Y

e) handling beyond forearm length Y Y

f) handling below knee length Y Y

g) handling above shoulder height N N

12: Is repeated, sustained or uncomfortable carrying,

pushing, or pulling of loads performed?

Y Y Y

13: Is sustained work performed when one arm reaches

forward or to the side without support?

N

14: Is there a repetition of:

a) similar work movements? Y Y

b) similar work movements beyond comfortable reaching

distance?

Y Y

15: Is repeated or sustained manual work performed?

Notice factors of importance as:

a) weight of working materials or tools Y Y

b) awkward grasping of working materials or tools Y Y

16: Are there high demands on visual capacity? N

17: Is repeated work with forearm and hand done with:

a) twisting movements? Y

b) forceful movements? Y

c) uncomfortable hand positions? N

d) switches or keyboards? N


45/102

41

Table 6. Rake Frame Shipfitter PLIBEL (continued)

Musculoskeletal Risk Factors Scores

Neck,

Shoulder,

and Upper

Back

Elbows,

Forearms,

Hands

Feet Knees and

Hips

Low Back

SUM 20 9 3 3 15

PERCENTAGE 76.9 81.8 37.5 37.5 71.4

Section II: Environmental / Organizational Risk Factors (Modifying)

Answer below questions, use to modify interpretation of musculoskeletal scores.

18: Is there no possibility to take breaks and pauses? N

19: Is there no possibility to choose order and type of

work tasks or pace of work?

Y

20: Is the job performed under time demands or

psychological stress?

Y

21: Can the work have unusual or expected situations? N

22: Are the following present?

a) cold N

b) heat Y

c) draft Y

d) noise Y

e) troublesome visual conditions Y

f) jerks, shakes, or vibration N

Environmental / Organizational Risk Factors Score

SUM 6

PERCENTAGE 60.0


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42

A2. RAKE FRAME WELDERS

Table 7. Rake Frame Welders RULA

Rapid Upper Limb Assessment (RULA)

(Matamney and Corlett, 1993)


11/9/99 Jeffboat Structural Shop Rake Frame Welding

RULA Component Frame #54600

Frame#

62130

Frame #

66600

Frame #

68580

Composite

(frames 53820

-- 73290)

Specific RULA

Score

Specific RULA

Score

Specific RULA

Score

Specific RULA

Score

Specific RULA

Score

Shoulder Extension/ Flexion m

flex

3 sl flex 2 sl flex 2 sl flex 2 sl flex

(53%)

2

Shoulder is Raised (+1) 0 0 0 0 0

Upper Arm Abducted (+1) 0 0 0 0 0

Arm supported, leaning (-1) -1 -1 -1 -1 -1

Elbow Extension/ Flexion neut 2 ext 1 ext 1 flex 2 ext

(61%)

1

Shoulder Abduction/ Adduction add 1 add 1 add 1 mod

abd

1 neut

(50%)

0

Shoulder Lateral/ Medial neut 0 m med 1 m med 1 m med 1 neut

(51%)

0

Wrist Extension/ Flexion ext 2 ext 2 ext 2 ext 2 ext

(64%)

2

Wrist Deviation

[Wrist Bent from Midline (+1)]

ulnar 1 rad 1 neut 0 ulnar 1 neut

(33%)

0

Wrist Bent from Midline (+1)

(taken care of by deviation)

0 0 0 0 0

Wrist Twist (+1) In mid range

(+2) End of range 1 1 1

1 1

Arm and Wrist Muscle Use Score

If posture mainly static (i.e. held for

longer than 10 minutes) or; If

action repeatedly occurs 4 times per

minute or more: (+ 1)

1 1 1 1 1

Arm and Wrist Force/Load Score

If load less than 2 kg

(intermittent): (+0)

If 2kg to 10 kg (intermittent): (+1)

If 2kg to 10 kg (static or

repeated): (+2)

If more than 10 kg load or

repeated or shocks: (+3)

2 2 2 2 2

Neck Extension/ Flexion 3 3 3 3 3


47/102

43

Table 7. Rake Frame Welders RULA (continued)

Neck Twist (+1) 0 0 0 0 0

Neck Side Bend (+1) 0 0 0 0 0

Trunk Extension/ Flexion hyp

flex

4 sl flex 2 hypflex

4 hyp

flex

4 hyp

flex

100%

4

Trunk Twist (+1) 0 0 0 0 0

Trunk Side Bend (+1) 0 0 0 0 0

Legs

If legs and feet are supported and

balanced: ( +1);

If not: (+2)

1 1 1 1 1

Neck, Trunk, and Leg Muscle Use

Score

If posture mainly static (i.e. held for

longer than 10 minutes) or; If

action repeatedly occurs 4 times per

minute or more: (+ 1)

1 1 1 1 1

Neck, Trunk, and Leg Force/ Load

Score

If load less than 2 kg


If 2kg to 10 kg


If 2kg to 10 kg (static or

repeated): (+2)

If more than 10 kg load or

repeated or shocks: (+3)

3 2 3 3 3

Total RULA Score 7 7 7 7 7

1 or 2 = Acceptable

3 or 4 = Investigate Further 5 or 6 = Investigate Further and Change Soon

7 = Investigate and Change Immediately


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44

Table 8. Rake Frame Welder Strain Index

Strain Index: Distal Upper Extremity Disorders Risk Assessment

(Moore and Garg, 1995)


11/9/99 Jeffboat Structural Shop Rake Frame Welding

1. Intensity of Exertion: An estimate of the strength required to perform the task one time. Circle the

rating after using the guidelines below; then fill in the corresponding multiplier in the bottom far right

box.

Rating

Criterion

% MS

(percentage

of maximal

strength)

Borg Scale(Compare to

Borgs Cr-

10 scale)

Perceived Effort Rating Multiplier

Light < 10% < or = 2 barely noticeable or relaxed

effort

1 1.0

Somewhat

Hard

10% - 29% 3 noticeable or definite

effort (84% of observed

time)

2 3.0

Hard 30% - 49% 4 - 5 obvious effort; unchanged

facial expression

3 6.0

Very Hard 50% - 79% 6 - 7 substantial effort; changes

to facial expression

4 9.0

Near

Maximal

> or = 80% >

pre-intervention quantitative risk factor analysis for ship construction processes

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